Leukemias affect about 60,000 individuals, and cause the death of 23,000 individuals annually in the US. The Leukemia SPORE renewal application builds upon progress achieved in the previous funding period, which contributed to a change in standards of care in leukemia. It focuses on four important novel mechanistic strategies which if successful, will establish new standards of therapies in leukemia: epigenetic therapy; immunotherapy with a new monoclonal antibody Hu-8F4; non-genotoxic p53 modulation by MDM2 inhibition; and improved FLT3 inhibitors therapies/ combinations in FLT3 ITD positive AML. Our overall goal is to discover/enhance these new therapies through better understanding of the causal pathophysiologies in leukemia and the identification of actionable targets. We propose four fully translational research projects (laboratory to clinic and back) supported by three cores. The overall Specific Aims include: 1) To optimize and improve the efficacy of epigenetic therapies in AIVIL (Project 1). This research area was developed by Project 1 co-leaders over the past 10 years, and resulted in the FDA approval of decitabine as an epigenetic therapy for MDS. The new aims investigate new targeted approaches to epigenetic therapy and clinical trials of novel, mechanism-based decitabine combinations in AML. 2) To explore anti-leukemic effects of a novel targeted immune therapy (Project 2). Previous work through this SPORE resulted in the development of the PRI vaccine. Project investigators will now test a newly discovered humanized T cell receptor-like antibody (8F4) with specificity for a conformational epitope of PR1 in vitro and in vivo, and conduct a phase 1 clinical trial of this novel monoclonal antibody to determine its anti- AML efficacy. 3) To explore strategies to enhance non-genotoxic p53 activation by MDIUI2 inhibition in AIVIL (Project 3). Previous work introduced p53-targeted therapy in leukemia with promising results. Investigators will now extend these findings using preclinical and clinical studies of novel MDM2 inhibitors and combinations, and further develop p53-targeted therapies of the leukemia microenvironment. 4) To investigate combined modality therapeutic strategies for the optimal use of 3rd generation FLT3 inhibitors (Project 4). SPORE investigators have championed the development of FLT3 inhibitors in AML, they now propose to study more potent FLT3 inhibitors as monotherapy and in combinations, as well as study crenolanib, a FLT3 inhibitor active against recently emerging and drug-resistant FLT3 point mutations.